The proposed research project is designed to yield information pertaining to (1) the epidemiological patterns of latent infections with simian viruses in primate tissues with special reference to simian cytomegaloviruses and foamy viruses, and (2) the pathogenicity and persistence of certain simian viruses with a model study on the pathogenesis of herpesvirus infection in experimental animals. The mechanism of viral latency, the mode of transmission, the immunological responses and the manifestation of slow chronic diseases will be pursued further.